Keeping roads safe is a priority for engineers from different fields. It is well-known that one of the main causes of traffic accidents is speeding. Therefore, traffic regulation agencies around the world utilize technological improvements such as speed detectors to impede drivers from speeding. Additionally, most vehicle manufacturers use light emitting diode (LED) headlights because of their special advantages, i.e., long life time, energy efficiency, and short rise time, which made them a suitable candidate to replace the existing lighting systems in the automotive industry. Furthermore, many research results show that due to inclement weather conditions and easiness of spotting oncoming traffic, daytime running lights in vehicles can decrease the accidents rate up to 28% for multi-vehicle and pedestrian accidents. Therefore, the automotive industry has started to equip their vehicles with daytime running lights, particularly for the vehicles with LED headlights due to being a power-efficient solution.
A well-known method for vehicle speed estimation is using the Radio Detection And Ranging (RADAR) system. Depending on the application and scenario, a RADAR system can be used for either detecting a moving object or estimating its speed [4]. A similar system (in principle) that uses the same technique of the RADAR but works on a different part of the electromagnetic radio spectrum is Light Detection And Ranging (LiDAR). The basic idea behind RADAR and LiDAR is to estimate speed from the frequency and travel time of reflected waves. Among various challenges, the beam-width and angle-of-arrival are the most critical ones and have high impact on the estimation accuracy of these systems [5]. Indeed, narrow beam-width is required for accurate speed estimations. It is also well-known that drivers can easily acquire the commercially available RADAR warning equipment/devices (as deeply explained in [6]). These devices detect the presence of RADAR/LiDAR (also known as speed gun or RADAR gun) and warn the driver to avoid traffic fines for speeding, which is illegal and an undesired situation. Further information about the limitations of state-of-the-art RADARs is given in [7].
In the context of Intelligent Transportation Systems (ITSs), researchers have been investigating the autonomous and smart vehicular to vehicular (V2V) communication in order to improve vehicles safety systems. The idea of using visible light communication (VLC) in the V2V communication is quite recent and has become attractive for various reasons; 1) availability of the hardware (LEDs) in vehicles, and 2) usage of a radio frequency (RF) system for the V2V communication can be inefficient due to interference, spectrum and power usage. There are numerous studies in the literature which have utilized VLC principles in V2V communication systems (see [8]-[14], references therein.)
Before proceeding to a description of the present invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.